The present invention concerns a means for automatically closing and opening the air intake duct of an oil burner as the burner stops and starts, said burner comprising a motor whence projects a shaft passing through the air intake duct, this shaft driving a fan and an oil pump, which feed air and oil into a mixer.
The problem encountered in oil burners of prior art is that the air duct remains open when the burner stops, whereby considerable air quantities pass through the firebox of the boiler, causing it to cool and resulting in appreciable loss of energy. The longer the non-operating times of the burner in proportion to the running periods, the greater will be the energy losses hereby incurred. If it were possible altogether to inhibit the air flow, this would mean in the heating of one-family houses and of small blocks of flats, in Finnish conditions and in the wintertime, a 12% oil saving and in the summertime a saving of 27%. Attempts have been made to prevent this cooling air flow e.g. by means of a damper mounted in the chimney and operated by a damper control motor. However, arrangements of this kind involve considerable detriments, one of them the risk that the damper fails to open or that it fails to close tightly, owing to soot and other dirt. In certain cases it has also happened that the pressure caused by heat rose to such high values that the ducts burst open explosively.